Combining MPDL3280A with adoptive cell immunotherapy exerts better antitumor effects against cervical cancer

Abstract

As the second most common gynecologic malignant tumors with a high mortality rate, cervical cancer jeopardizes women's life worldwide. The low cure rate in cervical cancer patients is mainly attributed to the lack of effective therapies. One feasible novel strategy is to develop immune-based approaches such as adoptive cell immunotherapy of DCCIKs which represents a promising nontoxic antineoplastic immunotherapy preferred in clinic practice. However, the therapeutic effect is not as efficient as anticipated. Possible explanations are tumors exploit immunoregulatory check-points such as programmed death 1(PD1)/PDL1 which provides tumor cells an escape strategy of circumventing immunologic rejection from immune surveillance by hampering activated tumor-specific T cell activities and rendering them functionally exhausted. With reduced transformation activity and enhanced antigenicity, a modified HPV16 E7 (HPV16mE7) was used to load DCs with silenced SOCS1 mediated by a recombinant adenovirus to improve the targetability and efficiency against cervical cancer. Combined with anti-PDL1 antibody MPDL3280A therapy, the co-cultured DCCIKs were transfused into murine models bearing tumor of HPV16 E6/E7 expressing CaSki cells for in vitro/in vivo antitumor activity assay. Although all of the animals succumbed to CaSki tumors even after adoptive DCCIKs transfer or MPDL3280A immunotherapy, the infusion of PDL1 blocking monoclonal antibody with activated T cells cured 40% of animals. These data support PDL1 blockade improves the efficacy of adoptive DCCIKs therapy, providing a new approach of immunotherapy against cervical cancer.

Keywords: DCCIKs; MPDL3280A; PDL1; SOCS1s; cervical cancer.

Figure 1.

The morphology of mature DCs After stimulated with TNF-α, HPVm16E7-pulsed DCs in irregular shape showed mature characteristics of larger soma with plenty of dendritic long and small bulges on their surfaces (400 × magnification). White arrow indicates long bulge and black arrow indicates small bulge.

Figure 2.

Cytotoxicity assay (A) Detected by flow cytometry, 23.6% CaSki cells expressed PDL1. (B)The cytotoxicity of effector cells at 10:1, 30:1 and 90:1 E/T ratios against CaSki cells was analyzed using CCK 8 assay. When lymphocytes incubated with MPDL3280A, DCCIKs increased the cytotoxic activity against CaSki cells with 37.9% at the E:T of 30 in relative to DCCIKs in the absence of MPDL3280A (p < 0 .01).

Figure 3.

In vivo antitumor activity analysis. (A) The therapeutic effect of DCCIKs in combination with MPDL3280A against mice bearing tumors was investigated in the groups of 10 BALB/C mice received 1×10⁶ CaSki cells. The therapy was initiated with normal human IgG, DCCIKs, MPDL3280A and DCCIKs in combination with MPDL3280A on day 7. Tumor volume and time experiment was analyzed using student's t-test. *p < 0.01(DCCIKs/MPDL3280A vs DCCIKs or MPDL3280A or IgG control); <0.05 (DCCIKs vs MPDL3280A or IgG control) (B) Survival rates were analyzed using the Kaplan-Meier method (log-rank test). The experiments were repeated, producing a significant statistical difference. *p < 0.01(DCCIKs/MPDL3280A vs DCCIKs or MPDL3280A or IgG control); <0.05 (DCCIKs vs MPDL3280A or IgG control).